Short-term deficits ease in Tasmania, but no relief for southwest WA

Australia recorded its wettest September on record in 2010. However, above-average rainfall
was largely in the north and the east of the country, missing the southwest corner, which is
experiencing its driest start to the year on record and its driest 12-month period on record
(see Special Climate Statement 21 and
22). Average to above average falls in southern
Tasmania in August and September were enough to remove deficiencies in this region in the
short-term. Northern and eastern parts of the country have continued to receive above to
very much above average rainfall, with the Northern Territory and Queensland having their
wettest September on record. Despite the dry conditions in the southwest, WA as a whole had
its third-wettest September on record due largely to unseasonable rains in the state's north
and east. Rainfall in recent months has cleared a number of short-term rainfall
deficiencies across eastern Australia. However, the rains in 2010 have only made limited inroads into
the serious deficiencies which remain on multi-year time-scales, especially in southeastern and
southwestern Australia and southeast Queensland, and continue to affect water supplies;
to alleviate these would require above average rainfall for a sustained period
(Special Climate Statement 22).

9-month rainfall deficiencies

For the 9-month period from January 2010 to September 2010, below average falls over the southwestern half
of WA during September 2010 has maintained areas of rainfall deficiency as described in the
previous drought statement.
Some average to above average falls over the Gascoyne and
Pilbara districts have slightly eased some areas of serious to severe deficiency, though
large areas still remain. To relieve these areas of rainfall deficiency in WA, i.e. to just
get above the tenth percentile, rainfall for the remaining three months of the year will
have to be very much above average,
i.e. in the highest 10% of such periods on record, over
large areas. In a coastal strip in the southwest corner between Lancelin and Walpole rainfall
for 2010 will be in the 10th percentile even if rainfall for the last quarter of the year
matches the highest on record.

Whilst recent rains in eastern Australia have provided, in many cases,
short-term relief, sustained periods of above-average rainfall are
needed to remove very long-term deficiencies. This is especially true
for the very long-term deficiency periods of 9 and 14 years (see the
Special Climate Statement 22).
Rainfall has been below average across
much of southwest and southeast Australia since 1997, whilst central and southern parts
of the Murray-Darling Basin have experienced below average rainfall since 2002.
These long-term deficiencies have taken place against a background of
well above average temperatures, including Australia's warmest decade on record.
Further information on exceptional rainfall
and temperature events across Australia can be found in the
Special Climate Statements.